Apparatus for use in diffusion transfer copying



J 1966 E. F. STIEVENART ETAL Q 3,257,926

APPARATUS FOR USE IN DIFFUSION TRANSFER COPYING Filed May 10, 1965 2 Sheets-Sheet l INVENTORS EM/EL FRANS STIEVENART HUGO FRANS DECON/NCK WA TSON. COLE GR/NDLE8 WATSON ATTORNEYS June 28, 1966 E. F. STIEVENART ETAL 3,257,926

APPARATUS FOR USE IN DIFFUSION TRANSFER COPYING Filed May 10, 1963 2 Sheets-Sheet 2 INVENTORS EM/EL FRANS ST/EVENART HUGO FRANS DECON/NCK BY WATSON, COLE GR/NDLE & WATSON ATTORNEYS 3,257,926 APPARATUS FOR USE IN DIFFUSION TRANSFER COPYING Emiel Frans Stievenart, Antwerp-Kiel, and Hugo Frans Deconinck, Antwerp, Belgium, assignors to Gevaert Photo-Producten N.V., Mortsel-Antwerp, Belgium, a Belgian company Filed May 10, 1963, Ser. No. 279,659 Claims priority, application Belgium May 14, 1962, 41,653, Patent 617,582 5 Claims. (Cl. 9589) The present invention relates to apparatus for use in copying documents by the silver complex diffusion transfer process.

In the performance of the silver complex diffusion transfer process, an image-wise exposed light-sensitive sheet, normally a sheet comprising a silver halide emulsion layer (hereinafter called the light-sensitive sheet), is treated with a liquid to bring about development of the latent image and is pressed against a sheet material (hereinafter called the receiving sheet) into which complexed silver halide diffuses from the light-sensitive material and is transformed to form another image of the printed text or other matter which is being copied.

If an exact predetermined positioning of the image on the receiving sheet is required, it is necessary to ensure printing.

Apparatus for use in carrying out the diffusion transfer process are known, which have means for relatively positioning both sheets prior'to their guidance into the deyeloping bath. The operation of these apparatus, however, is not quite accurate, since in practice it is very difiicult to make both sheets follow reproducible paths through the apparatus before they are pressed together and the diffusion transfer takes place.

According to the present invention, an'apparatus for use in copying by the silver complex diffusion transfer process comprises guide means for guiding a light-sensitive sheetthrough a developing Zone, means for guiding a receiving sheet through or adjacent said Zone, so that this sheet faces but is spaced from said light-sensitive sheet, sheet-pressing and sheet-driving means at the exit of said zone for pressing said light-sensitive sheet and said re ceiving sheet together and for driving said pressed sheets out of the apparatus, and sheet aligning means comprising stops located in the paths of travel of such sheets immediately before the pressing means in the direction of sheet travel, the said stops being displaceable. from a closed position blocking the passageof the sheets to an opened position permitting the leading edges of the two sheets to advance and to enter between the sheet-pressing means, by pressure transmitted thereto by the leading edges of both said sheets.

Preferably the developing Zone comprises a container holding a developing liquid or activator, the said guide means for the light-sensitive sheet being arranged so as to guide the light-sensitive sheet through the body of liquid in the container. The guide means may provide for the guidance of a receiving sheet also through the said body of liquid or above the surface thereof.

Registering of the sheets in the transverse direction, i.e. normal to the direction of sheet travel may be facilitated in a known way by one or more side edge guides.

United States Patent 7 Patented June 28, 1966 ice The guide means for one of the sheets, is preferably arranged so as to permit or facilitate the buckling of the said sheet when it abuts against the closed stops before said stops are contacted by the second sheet. The first sheet fails to displace the stops until the second sheet abuts against them.

It is thus the second sheet which controls the displacing of the stops, and the leading edge of the second sheet is followed in alignment 'by the leading edge of the first sheet since the latter is moving forward against the stops under influence of its buckled part.

It is thus clear that even considerable'dilferences in the alignment of the leading edges of the sheets may exist when they are introduced into or move through the apparatus. At any rate the stops will block the passage of the first sheet untilthe second sheet will be inalignment with the first sheet. 7

With reference to the drawings the invention will now be described by way of example.

FIG. 1 represents a longitudinal section. ofthe appa ratus.

FIG. 2 is a view of the paths followed by the sheets.

FIG. 3 is a cross-section of the apparatus on line 33 of FIG. 1.

FIG. 4 is a modified embodiment of the blocking elements.

FIG. 5 is a cross-section of the blocking element on line 5--5 of FIG. 4.

FIG. 1 represents an apparatus for preparing aluminum printing plates according to the silver complex diffusion transfer p'rocess, comprising a developing tank 11, two guide plates 12, 13 and a continuously driven outlet roller pair 15, 16. The guide plates guide a light-sensitive sheet 27, and a receiving sheet (aluminum sheet) 28 intothe position as shown in FIG. 1, such as torsion springs 39, 40 imbedded at one end in shaft 19 and at the other bearing against the cams 17, 18.

On the. shaft 19 are also mounted the freely rotatable roller sections 20 and 21 which press against the roller sections 22, 23 mounted in the same free rotating manner on the shaft 24.

The shafts 19 and 24 are positioned in a frame (not shown inthe figures) permitting in a simple way the removal of the entire alignment system from the apparatus, so that the lattercan be used for preparing prints according to the. classical method.

The surface of the roller sections 20, 21, 22 is covered with a resilient material. The alignment system is represented in cross-sectional view in FIG. 3.

Finally, the guide plate 12 is provided with the curved part 25 adjacent the alignment system.

Now the operation of the apparatus will be described.

One end edge of an image-wise exposed light-sensitive sheet 27, emulsion side turned downwardly, is placed into the upper notch of the element 14. Similarly, one

end edge of an aluminum sheet 28 is placed in the lower notch of said element 14. Both sheets are kept in a generally horizontal position and at the moment both end edges bottom in the notches of the element 14, the side edges are aligned and held immovab-ly in respect to each other by the operator. Next, the sheets are withdrawn and guided, with those end edges which had been slid into the notches of the element 14 in leading position 3 into the developing tank 11 so that the light-sensitive sheet 27 advances over the guide plate 12 and the aluminum sheet 28 advances between the guide plates 12 and 13.

The depth of the notches of the element 14 is such that, considering the length of the paths followed by the sheets through the developing tank 11, the light-sensitive sheet 27 will arrive at the aligning element, i.e. the cams 17-18, before the aluminum sheet 28.

Due to its lesser stiffness the light-sensitive sheet does not succeed in displacing the cams and is leading edge will buckle so that it takes the position 29 as illustrated in FIG. 2, therein helped by the curved part 25 of the guide plate 12. This curved part is preferably determined in experimental or empirical way.

Owing to its greater stiffness the aluminum sheet 28, at the moment of its abutment against the cams 17, 18 during the movement of thesheets through the developing tank, will overcome the resistance of the spring means holding the cams, displace the cams and abut against the pressure roller sections 20, 22 and 21, 23. During this movementthe leading edge of the light sensitive sheet 27 will follow the aluminum sheet 28 since due to the formed buckling 29, the leading edge of the light-sensitive sheet is urged against the cams and consequently will promptly follow up any displacement of said cams.

When entering between the roller sections, the leading edges of both sheets are partly pressed together whereby any further relative displacement of the sheets is excluded, since the emulsion layer of the light-sensitive sheet 27, due to its guidance through the developing tank, has been strongly swollen so that it will strongly adhere to the aluminum sheet 28.

Both sheets are still further pushed into the apparatus by the operator until they finally reach between the driven outlet roller pair 15, 16. This roller pair presses both sheets firmly together all over their full length, removing thereby the superfluous developing liquid. After leaving the apparatus the sheets are stripped off from each other after a short while and the positive print is now obtained on the aluminum sheet.

Next, this sheet is treated with an appropriate lithographic composition whereupon it is ready for being attached onto the pressing roller of an aluminum offset printing press.

As a further advantage of the notches it may be cited that they allow the operator of the aparatus to manage that both sheets are guided in straight direction through the apparatus. Care has only to be taken that, in case the aluminum sheet as a consequence of an oblique or non-straight introduction in the apparatus abuts against only one of the cams, the operator will not continue pushing but slightly turn both sheets until he feels the aluminum sheet abut also against the second cam. At that moment both sheets may be pushed further through the apparatus.

According to a modified embodiment represented in FIGS. 4 and two roller sections 32 and 33 have a noncircular cross-section. They are mounted in such a way that they are contacting the other roller sections 30 and 31 only at the beginning of the operation.

Compared with the first embodiment this modified embodiment shows the advantage that only the leading edges of both sheets are pressed together after the alignment by the notches. In practice this embodiment has shown to be an effective method because the adhesive power of the swollen gelatin emulsion layer of the lightsensitive sheet suffices for firmly adhering both sheets together, even when they are only pressed together with their leading edges.

Moreover, this method has the advantage of preventing a premature diffusion transfer which can take place owing to the pressing together of both sheets all over the width of the roller sections, therebycausing longitudinal strips if differing density on the positive print of the aluminum sheet.

Before introducing the light-sensitive sheet and the aluminum sheet into the apparatus, the roller sections 32 and 33 must be brought into operative position, i-.e. they must press against the roller sections 30, 31 in a position as represented in FIG. 5. Said position is obtained by lifting the brace shaped member 34, mounted in a freely movable way on the shaft 24, thereby also lifting by means of the transverse bar 36 the pins 37, 38 fitted on top of the roller sections 32, 33.

Upon introducing both sheets into the apparatus they first abut with the leading edges against the cams 17, 18, and after displacement of the cams, also against the [roller sections 30, 32 and 31, 33.

The leading edges are pressed between the roller section and make these roller sections carry out a rotating movement. After a rotating movement of about 90 the contact between the roller sections 30, 32 and 31, 33 is interrupted and the sheets are no longer pressed against each other during the further advancing through the apparatus. The sheets pass between the rollers 15 and 16 where they are firmly pressed together and where the diffusion transfer starts.

Upon the introduction of the sheets into the apparatus, the pins 37 and 38 are pushed against the transverse bar 36 so that the brace shaped member 34 fall down and close the entrance to the apparatus. Before starting a following operation the operator is therefore forced to restore this member 34 in its upward position, whereby the roller sections 32, 33 are set again in pressing position on the roller sections 30, 31.

' The examples described hereinbefore are only to be considered as possible embodiments and in no way limit the invention thereto.

In the said examples, the system comprising the roller sections was more intended for being used in existing apparatus comprising guide plates such as 12-13 and an outlet roller pair such as 1516.

When designing a new apparatus it is possible to omit the roller sections which have been described hereinbefore, and have the action of the sheet pressing and of the sheet driving means at the exit end of the apparatus fulfilled by one roller pair only, e.g. a roller pair such as 15-16 which has been described hereinbefore. In such case, however, it will be necessary to provide the stops in the immediate presence, or on one of the shafts, of said roller pair.

We claim:

1. In an apparatus for copying by the silver complex diffusion transfer process having guide means for guiding a light-sensitive sheet along a path extending through a developing zone, means for guiding a receiving sheet along a path extending at least adjacent said Zone, so that adjacent sides of the two sheets are in mutually facing spaced relationship, sheet-pressing and sheet-driving means arranged at the exit end of said zone for pressing said two sheets together and for advancing said pressed sheets out of the apparatus, and sheet aligning means, the improvement wherein said aligning means comprises stop means located in the paths of such sheets immediately in advance of the nip of the pressing means in the direction of sheet travel, said stop means being displaceable from a closed position blocking further passage of the sheets to an open position permitting the leadingedges of the sheets to advance and enter the sheet-pressing means, and spring means urging the stop means normally to said closed position, the force of said spring means being greater than the resistance to buckling of the leading sheet but less than such resistance of the two sheets combined whereby said spring means yields to open said stop means only where the leading edges of the two come into substantial alignment.

.2. An apparatus according to claim 1, wherein the said stops consist of two cams which are independently fitted on a common shaft, and which are kept in the closed position by spring means.

. 3. An apparatus according to claim 1, wherein one of the guide means for guiding the sheets through the developing zone is arranged in such a Way so as to permit the buckling of the sheet which is guided by same, when said sheet abuts with its leading edge against the closed. stops, said stops being not yet contacted by the leading edge of the second sheet.

4. An apparatus according to claim 1, wherein the sheet-pressing means consist of 2 pairs of non-driven roller sections.

5. An apparatus according to claim 4, wherein one roller section of each roller'section pair, has a non-circular cross-section. I

References Cited by the Examiner UNITED STATES PATENTS 2,810,331 10/1957 Van der Grinten 98-89 2,865,275 12/1958 Ruijs 95-89 FOREIGN PATENTS 1,102,558 3/1961 Germany.

10 NORTON ANSHER, Primary Examiner.

C. B. PRICE, JR.,Assistant Examiner. 

1. AN AN APPARATUS FOR COPYING BY THE SILVER COMPLEX DIFFUSION TRANSFER PROCESS HAVING GUIDE MEANS FOR GUIDING A LIGHT-SENSITIVE SHEET ALONG A PATH EXTENDING THROUGH A DEVELOPING ZONE, MEANS FOR GUIDING A RECEIVING SHEET ALONG A PATH EXTENDING AT LEAST ADJACENT SAID ZONE, SO THAT ADJACENT SIDES OF THE TWO SHEETS ARE IN MUTUALLY FACING SPACED RELATIONSHIP, SHEET-PRESSING AND SHEET-DRIVING MEANS ARRANGED AT THE EXIT END OF SAID ZONE OF PRESSING SAID TWO SHEETS TOGETHER AND FOR ADVANCING SAID PRESSED SHEETS OUT OF THE APPARATUS, AND SHEET ALIGNING MEANS, THE IMPROVEMENT WHEREIN SAID ALIGNING MEANS COMPRISES STOP MEANS LOCATED IN THE PATHS OF SUCH SHEETS IMMEDIATELY IN ADVANCE OF THE NIP OF THE PRESSING MEANS IN THE DIRECTION OF SHEET TRAVEL, SAID STOP MEANS BEING DISPLACEABLE FROM A CLOSED POSITION BLOCKING FURTHER PASSAGE OF THE SHEETS TO AN OPEN POSITION PERMITTING THE LEADING EDGES OF THE SHEETS TO ADVANCE AND ENTER THE SHEET-PRESSING MEANS, AND SPRING MEANS URGING THE STOP MEANS NORMALLY TO SAID CLOSED POSITION, THE FORCE OF SAID SPRING MEANS BEING GREATER THAN THE RESISTANCE TO BUCKING OF THE LEADING SHEET BUT LESS THAN SUCH RESISTANCE OF THE TWO SHEETS COMBINED WHEREBY SAID SPRING MEANS YIELDS TO OPEN SAID STOP MEANS ONLY WHERE THE LEADING EDGES OF THE TWO COME INTO SUBSTANTIAL ALIGNMENT. 